I can understand your concern. I did actually consider mentioning
something about skipping stops.. but I forgot to, I spent a good few
hours on the original, so I guess my thoughts got easily distracted.
I'll make an example based on the real data to help illustrate the idea,
but I'll also include an imaginary express version that only stops at a
few major stops. provided everything goes as planned I'll link to a
fairly realistic example in version 4 (I need version 3 to fix a mistake
I made). I understand that you may not want to follow each version due
to being busy or whatever, so until the example is ready any future
version will be 3.x (so for example: 3.0,3.1,3.2...); this way you'll be
able to Ctrl+f and search for '#4', if there's no #4 it isn't ready yet
and so you won't waste your time reading through the changelog for it.
as for seeing all the stops/being able to compare to official feeds,
that may fall more under what the renderer is expected to do, as it
should already be reading all the segments as one whole route.
On 3/15/19 6:30 PM, Jo wrote:
When I start mapping a bus line, I have several route relations which
contain all the stops for each variation in itinerary.
When I add the ways, it would be nice to reuse subroute relations for
the parts where ways are shared between lines.
When I come back later and I want to compare whether the number of
variations for a line is still the same, I want to compare against
sequences of stops in the route relations, hence the reason why I
would not add the stops to the subroute segments. (Compare against
data from the operator or GTFS)
We also have 'express' lines that skip stops. if the stops are put in
the subroute relations, then they can not be reused for those lines.
As far as I'm concerned, the sequence of stops is the 'signature'
defining each variation in itinerary.
Polyglot
On Fri, Mar 15, 2019 at 6:55 PM seirra blake
<sophietheopos...@yandex.com <mailto:sophietheopos...@yandex.com>> wrote:
key: almost tagging should occur here | data may be reused in
parent | data may be reused in parent and any 'adjacent' (with the
same letter) parent
/public transport network///[A]/
/
/route_master=public transport /[B]
/route variant/ [C]
_combined stop/way relation suitable for public
transport v2_ [E]
_*shared way relation*_ [G]
/road network///[A]/
/
/road /[C]
_*shared way relation*_ [G]*
*
/cycle network//**/[A]/*
*/
/cycle route /[C]
__
__
*_shared way relation_* [G]
_____________________________________________________________________________
potential new tags that may be required:
[C]: shared=yes (to tell the software there is use of shared ways,
but the software probably should be able to work that out)
[E/F/G]: route=shared (this is considered in case type=route
explicitly requires a route=* key)
_____________________________________________________________________________
notes:
* [G] may be infinitely nested as required to prevent duplicate
sets of ways (although this should rarely be required)
* [G] may require names in some cases and should always require
type=route, but should include no other tags unless it very
specifically relates to only the members of the relation and
can't be included in any parent relation (unicorns are
probably more common)
* [G] should almost always not be used for a single way unless
it will assist in maintainability. if a
* I don't believe route_master=public transport actually exists,
but the same concept should work for any public transport
* the route=* tag should not be required until you move up to
[C], shared way relations and bus stop relations should be
open to any route type to increase re-usability
* as they are just a connected line of ways, shared way
relations should be usable in either direction, the direction
to use could be specified via a role. although reusable for
routes going in the same direction, [E] will rarely be
reusable for both directions of a route because it contains
both platforms and stops, and platforms usually differ
depending on direction.
* if this becomes accepted it may become a good idea to specify
a members limit for relations (at which point it should be
split up). such ways should probably
* I may consider adding a rough idea on perceived pros/cons,
depending on demand
* I may add a more visual version, depending on demand
* I may add an actual example, depending on demand (if you wish
to add your own as well, or an inspired version please base it
heavily on reality if it is on main OSM. do not make any
existing route relations unusable)
_____________________________________________________________________________
changelog:
#0
* initial concept
#1
* removed [D] and [F]. [D] was meant to be removed prior to
sending, [F] is not required.
* added a few more notes so it may be referred to on its own
* the bus example applies to any public transport really, adjust
language accordingly
* warned against damaging existing relations' usability/the
creation of fictional data
* added extra details on a request if needed basis
* added this changelog and relevant versioning to help people
keep track. this should be traceable to the (unlabelled) version 0
special thanks:
* you may request your name here and optionally credits for
ideas you contributed (being kept in an opt in basis in case
people don't want their names shown)
On 3/15/19 2:37 PM, seirra blake wrote:
I can see *a lot* of shared routes in my area because most of the
buses heavily use a star topography (everything must take you to
a central station) as opposed to a hybrid mesh/star topography
(everywhere has access to a service to a central station, but
there are circular routes to allow quicker travel in some
circumstances). for example my local service has one incredibly
early train station detour (presumably for long distance
commuters), the two main routes (incoming/outgoing) and a route
that stops at the bus depot. all 4 of these routes share a large
part of it and that's just one route number! such route segments
could help shrink and simplify maintaining the relations a lot.
for example if there's a detour due to roadworks, you don't have
to edit the very large number of relations individually, (our bus
station has around 20 bays, each taking multiple services...)
just the shared child relations. I don't think we need a
specially labelled super route relation, but perhaps we do need a
way to tell the data user that a segment is shared. these are the
problems I see:
1. where do the tags go?
2. do you need a separate one for each direction?
3. is type=super_route or similar the best idea?
4. how far can they nest?
5. a shared route is being used for public transport, should the
stop positions and bus stops be included with all the ways?
so... what do we do? this is what I see as a solution:
1. if a route is shared, tags should be minimal and only related
to the physical route itself perhaps not even including the
usual route tag (AFAIK wouldn't just about any route relation
in existence define the route tag? so this would just be
another pointer to the software that this isn't your regular
route. but maybe it still is best to tag it, in which
case.... maybe route=shared?), rather than things such as
what bus routes it is part or anything, this can easily be
seen simply by looking at parent relations
2. maybe use the roles forward/backward? I don't think these are
used for much any more
3. what do we gain? I think this can more easily be solved by
simply adding another tag such as shared=yes which can tell
the software that there are route relations that are intended
to be treated as just one big way. see below for a more
detailed explanation.
4. I don't see a reason to limit the nesting, I imagine in most
use cases, the benefit of sharing duplicate relation data
probably outweighs any impact from processing nesting
5. if a shared route is used for both a numbered road route and
public transport it's probably unfair on the road user that
doesn't need them if they are included. also this would make
it difficult to work out where to place it in a public
transport V2 relation.. as they have stops at the top, ways
at the bottom but this has both!
so here's an indented, somewhat simplified example of how it
roughly would nest based on the idea of a public transport route,
a cycle route and a road relation that share the same set of ways
(_underlined_=can be shared in parent nesting level, *bold*=can
be shared in nesting levels outside of the parent one, italic=the
level at which main tagging should occur. for easier referencing
each equivalent level of nesting has been assigned a letter):
_______________________________________________________________________________
/bus network///[A]/
/
/route_master=bus /[B]
/route variant/ [C]
_*route segments*_ [D]
_combined bus stop/way relation suitable for
public transport v2_ [E]
_shared bus stop relation_ [F]_
_
_*shared way relation*_ [G]
/road network///[A]/
/
/road /[C]
_*shared way relation*_ [G]*
*
/cycle network//**/[A]/*
*/
/cycle route /[C]
__
__
*_shared way relation_* [G]
_____________________________________________________________________________
potential new tags that may be required:
[C]: shared=yes (defaults to no)
[E/F/G]: route=shared (this is questionable in terms of benefits
though)
_____________________________________________________________________________
notes:
[G] may be infinitely nested as required to prevent duplicate
sets of ways (although this should rarely be required)
as you can see, this allows a lot of the data to be shared
between the various types of relations, whilst also allowing
current relation structure to remain the same, this is just an
extra higher level of detail, where required. due to the way
public transport relations are handled it may be required to even
have every segment in [D] contained in a relation, however as
cycle and road relations are purely made up of ways they may not
need the same kind of treatment and be able to mix items from [G]
with directly referenced ways. the separation of bus stop and way
data allows public transport relations to still correctly
identify the different bus stops in each direction but not have
to duplicate the way data. the naming of parts is solved, as this
can be applied to [G] level relations. the use of [G] and [C]
would help solve where routes need to be split up to keep
maintenance possible. [E], [F] and [G] theoretically shouldn't
need to be tagged as the fact they include any child relations at
all should be enough to indicate what they are, however if not
route=shared would certainly make it obvious. I hope this theory
on how we could solve it was helpful, if any further
clarification is required or there's a notable mistake/error
please let me know and I'll try to respond as best as I can to
that. I have thought about perhaps making an example of this, if
it would help please let me know.
**
On 3/15/19 12:07 PM, marc marc wrote:
Le 15.03.19 à 12:27, Hufkratzer a écrit :
is that a good/sufficient reason to define a new relation type?
imho nearly no routing tools (nor foot nor bus) is currently able
to use a relation type=route with relations as child.
so that's a good reason to create/improve a doc if superrelation is
needed for ex for routing (of course maybe some mapper need superroute
only for the fun of having a relation that collect all other).
for ex how a "data user" can detect "it 's a superroute" <> "it's 2
route with a shared segment" ?
for the moment, the trick is to notice that the name of the main
relationship is close to the name of the children's relationships
and to know that the names of all these children's relationships
are fake names (which should therefore be removed/corrected).
there is for ex nothing called "European long distance path E4 - part
France". it's an artificial name to descript how the relation is splited
maybe the tag network should be the same and/or the name (the country
XYZ may move the a scope tag)
the main relation must/should/mustn't/shouldn't have all/some same tag
as the child ?
all/a lot of child tag must move to the main relation only ? (that's
what we do with MP : we don't duplicate alls tags to way + relation)
etc...
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